1. Field of the Invention
This invention relates generally to escapements, and more particularly, to an escapement which allows incremental amounts of motion of an output shaft at a high torque.
2. Disclosure Information
Escapement devices often use an oscillating member. The oscillating member has a pair of prongs that alternately engage teeth of a rotatable sprocket. The sprocket is rigidly connected to an output member. The output member is often spring biased to rotate such that when the oscillating member swings and disengages its one prong from a tooth of the sprocket, the sprocket immediately rotates until another tooth thereof engages the other prong. Such oscillating devices can be seen in U.S. Pat. No. 3,316,769 issued to Nordin on May 2, 1967; U.S. Pat. No. 2,907,067 issued to Olsen on Oct. 6, 1959 and U.S. Pat. No. 3,063,297 issued to Hyde on Nov. 13, 1962.
Other escapement devices have been devised to to eliminate the oscillating pendulum motion. One device is disclosed in U.S. Pat. No. 2,871,702 issued to Tetro on Feb. 3, 1959 which has an output member and an input member both connected to a spring which is preloaded. The input member has a cam which engages an intermediate sliding block which is forced to disengage from varius stops mounted on the escapement housing after a predetermined amount of rotation of the input member. The output member is then free to rotate with the sliding block until the sliding plate reengages a succeeding stop. The input member is again rotated to rewind the spring and disengage the sliding block from the stop.
Another sliding block escapement device is disclosed in U.S. Pat. No. 3,640,142 issued to Stafford on Feb. 8, 1972. The Stafford patent discloses an input member which is connected to the spring that drives the output member.